Such a ventilation valve arrangement is, for example, known from U.S. Pat. No. 6,763,677 B1. Such a ventilation valve arrangement is often also called “butterfly valve”. The two valve openings are arranged in two quadrants of a circle. In the two other quadrants of the circle, the valve plate is impermeable. The valve element has a similar embodiment, that is, it has a circular embodiment, in which openings are arranged in two quadrants. If the openings in the valve element come to overlap the valve openings, the ventilation valve arrangement is completely open. If, however, the closed quadrants of the valve element cover the valve openings, the ventilation valve arrangement is closed. Interim positions are possible. One of the valve openings is connected to the suction side of a ventilation system, and the other valve opening is connected to the pressure side, so that an air exchange with the inside of a container can take place via the two valve openings. The fresh air supplied is mixed with an air flow circulating in the container. For this purpose, the ventilation valve arrangement is built into the front wall of a transport container. The opening degree of the valve arrangement is set manually.
U.S. Pat. No. 7,171,821 B2 shows a temperature control unit with a ventilation arrangement, in which a check valve is provided, which closes an opening or releases it with different opening degrees. This check valve can be stopped in different angle positions. Sensors are provided to warn an operating staff that the ventilation valve arrangement should be adjusted. However, this is relatively elaborate.
From U.S. Pat. No. 6,595,847 B1 is known a solution for a ventilation valve arrangement, in which the check valve can be adjusted by means of a motor. The motor turns a handle, which again activates the check valve. Such a motor design is expensive, at least when it has to influence a relatively large valve opening.